The present invention is directed to ice detection systems, in general, and more particularly, to an advanced warning ice detection system for use on-board an aircraft during flight.
For aircraft application, inflight ice detection is limited to in-situ sensors, like the Ice Detector manufactured and marketed by Rosemount Aerospace, Inc. bearing model no. 871, for example, which is mounted on the aircraft surface to sense a collection of ice on a vibrating element. A ground-based ice detection system known as the IceHawk(copyright) system, marketed and manufactured by the Sensor Systems Division of Goodrich Corporation, detects accreated ice on the surface of an aircraft visually by laser polarization scanning techniques. Both of these type systems detect ice after it has accreated on the aircraft surface and thus, requires de-icing to restore the surface to its intended state. Neither system can predict ice accretion prior to the formation on the aircraft surface or before the aircraft enters an icing region of airspace during flight.
A UV Raman LIDAR which is an active, ground-based, laser remote sensing instrument measures vertical profiles of the atmosphere above the site of the instrument for water-vapor mixing ratio and several cloud- and aerosol-related quantities. Such a system, which is known as CART (Cloud and Radiation Testbed), is currently being developed by the Sandia National Laboratories for the atmospheric radiation monitoring (ARM) project and is described at the website  less than  less than RL Instrument.htm greater than  greater than . While operational at a southern great plains site, the ground-based Raman LIDAR instrument remains a test bed for obtaining atmospheric measurements for climate research. It includes a very large sized receiver telescope and laser transmitter to achieve the long range and precision necessary for extensive profiling of the atmosphere.
Accordingly, it is desirable to have a warning system small enough in size to be mountable on-board an aircraft and powered thereby and which has the capability of inflight monitoring the airspace ahead of the aircraft for conditions likely to cause ice accretion on the surface of the aircraft and warn the pilot and crew of such an impending condition in sufficient time to change the heading of the aircraft and avoid the icing region of airspace. It would be also desirable for such a system to be able to share certain elements of one or more existing air data and obstacle awareness measuring systems already on-board an aircraft to reduce the cost, size, weight, and power requirements thereof.
In accordance with one aspect of the present invention, a warning system mountable on board an aircraft for inflight monitoring of the airspace ahead of the aircraft for conditions likely to cause ice accretion on the surface of the aircraft and provide a warning thereof comprises: a laser source for generating a pulsed laser beam at a first wavelength; a first plurality of optical elements configured to direct the pulsed laser beam into the airspace ahead of the aircraft; a second plurality of optical elements for receiving the backscattering of light from the pulsed laser beam, the second plurality of optical elements configured to separate the received backscattering of light into a plurality of predetermined wavelengths; a plurality of light detectors for detecting the light of the separated plurality of wavelengths, respectively, and generating respectively corresponding plurality of electrical signals representative of the light detected thereby; and a processor for processing the plurality of electrical signals to determine if airspace conditions ahead of the aircraft are likely to cause ice accretion on the surface of the aircraft, and for generating a warning indicative thereof.
In accordance with another aspect of the present invention, the first plurality of optical elements of the warning system is configured to direct the pulsed laser beam along a first optical path; the warning system includes an optical scanner disposed in the first optical path and operative to scan the pulsed laser beam into the airspace ahead of the aircraft with a predetermined scan pattern, the scanner also operative to receive the backscattering of light from the pulsed laser beam and direct said backscattering along a second optical path; and the second plurality of optical elements of the warning system is configured to receive the backscattering of light from the second optical path and to separate the received backscattering of light into the plurality of predetermined wavelengths.